Elevator doors usually consist of a car door, which is connected with an elevator car, and a plurality of shaft doors, which are arranged on floors of a building and afford access to the shaft of the elevator. On opening and closing, the car door and the shaft door are connected together by way of a coupling and moved in common by the door drive mounted on the elevator car.
Elevator doors as used in, for example, high-speed elevators, have to meet various preconditions. Thus, shortest possible door closing times are desired by customers so as to achieve high levels of transport performance. The document EP 0 548 505 B1 discloses a method for rapid opening and closing of the elevator doors in accordance with a travel curve. The travel curve contains data about duration and speed of the opening and closing of the elevator doors as well as with respect to kinetic energy of the elevator doors during these processes. Depending on the respective wind conditions prevailing in the shaft, the elevator doors can close with greater or lesser expenditure of force and time, which impairs the transport performance.
U.S. Pat. No. 3,822,767A teaches detection of the wind speed prevailing in the shaft and a proportional adaptation of the magnitude of the closing force of the door drive, which moves the elevator doors, to the strength of the wind speed prevailing in the shaft.
A travel curve, in fact, usually consists of several phases and, in particular, of an acceleration phase, a glide phase and a braking phase, wherein different closing forces prevail just in all three phases. In the acceleration phase and the braking phase the elevator doors are moved with high closing forces, but in the glide phase the elevator doors are moved only with low closing forces. The travel curve is therefore not optimally matched to the pressure relationships, during opening and closing of the elevator doors, through a proportional adaptation of the magnitude of the closing force of the door drive. Thus, an excessively rapid opening and closing of the elevator doors causes an unnecessarily high consumption of electric power and leads to rapid wear of the elevator doors, which in turn increases maintenance costs of the elevator installation and also impairs serviceability of the elevator installation.